Diarrhoea DDx

Diarrhoea – Differential Diagnosis

Common causes

• Gastroenteritis
  • Viral
  • Bacterial
• Toddler’s diarrhoea
• Traveller’s diarrhoea
• Irritable bowel syndrome
• Lactose intolerance
• Faecal impaction

Must Not Miss

• Colorectal cancer
• Crohn’s dis/ Ulcerative colitis
• Diverticulitis
• Intussusception
• Pelvic abscess
• HIV

Easily missed

• Medication
• Hyperthyroidism
• Diabetic autonomic neuropathy
• Coeliac disease
• Short bowel syndrome
• Pancreatic insufficiency
• Addison’s disease

Red flags

• Weight loss
• Systemic features (fever, night sweats, anorexia)
• Persistent vomiting
• Abdominal pain
• Persistent altered bowel habit: age > 50 years
• Rectal bleeding
• Iron deficiency anaemia
• Raised inflammatory markers
• Nocturnal symptoms disturbing sleep
• Family history of bowel cancer
• Foreign travel

Investigations to consider

• FBC, CRP/ESR
• U&Es, LFTs, TFTs
• Coeliac screen
• Stool microscopy and culture
• Urinalysis
• HIV screen
• Barium enema
• Sigmoidoscopy/Colonoscopy
• Malabsorption screen